Optimization of Cu(II)-ion imprinted nanoparticles for trace monitoring of copper in water and fish samples using a Box–Behnken design

We describe a nanoparticles ion-imprinted polymer (IIP) for the selective preconcentration of copper (II) ions. It was obtained by precipitation polymerization from 2-vinylpyridine (the functional monomer), ethylene glycol dimethacrylate (the cross-linker), 2,2′-azobisisobutyronitrile (the initiator), 2,9-dimethyl-1,10-phenanthroline (the copper-binding ligand) and nickel nitrate (the template ion) in acetonitrile solution. The IIP particles were characterized by Fourier Transformed Infra Red Spectroscopy (FTIR), thermogravimetric and differential thermal analysis, and by scanning electron microscopy. The optimization process was carried out using the Box–Behnken design (BBD). Effects of several factors such as solution pH for adsorption, amount of polymer, type, concentration and volume of eluent for extraction, as well as adsorption and desorption times were investigated. Under the optimum conditions (type and concentration of eluent, HCl 1.6 mol L^?1; volume of eluent, 6 mL; adsorption solution pH, 6.0; amount of polymer, 30 mg; adsorption time, 25 min; desorption time, 25 min), preconcentration factor of the proposed method was approximately 100. Under the optimized conditions, the detection limit was found to be 0.1 μg L^?1, while the relative standard deviation (RSD) for six replicate measurements was calculated to be <4%.     

Comparison of essential oil compositions of Salvia mirzayanii obtained by supercritical carbon dioxide extraction and hydrodistillation methods

Essential oil of Salvia mirzayanii cultivated in Iran was obtained by hydrodistillation and supercritical (carbon dioxide) extraction methods. The oil was analysed by capillary gas chromatography using flame ionization and mass spectrometric detections. The compounds were identified according to their retention indices and mass spectra (EI, 70 eV). The effects of different parameters such as pressure, temperature, modifier volume and extraction times (dynamic and static) on the supercritical fluid extraction (SFE) of S. mirzayanii oil were investigated. The results showed that, under a pressure of 35.5 MPa, temperature of 35 °C, 6% methanol, dynamic extraction time of 50 min and static extraction time of 30 min, extraction was more selective for the linalyl acetate. Thirty four compounds were identified in the hydrodistilled oil. The major components of S. mirzayanii were linalyl acetate (7.6%), 1,8-cineole (8.0%), linalool (9.0%) and 8-acetoxy linalool (11.0%). However, by using supercritical carbon dioxide in optimum conditions, only three components contain more than 63% of the oil. The yield of the obtained oil based on hydrodistillation was 2.20% (v/w). Extraction yield based on the SFE varied in the range of 1.50–9.67% (w/w) under different conditions. The results revealed that, in Iranian S. mirzayanii oil, linalyl acetate is a major component.     

Synthesis and Assessment of Novel Gelatin–Chitosan Lactate Cohydrogels for Controlled Delivery and Tissue Engineering Applications

The current study discusses the synthesis of novel gelatin–chitosan lactate cohydrogels. Mechanical studies indicated the viscoelastic nature of the cohydrogels. The cohydrogels were predominantly elastic in nature. Inherent mechanical stability of the cohydrogels was better than the pristine gelatin hydrogel. Incorporation of chitosan lactate improved the in vitro swelling and the drug release properties of the cohydrogels. The cohydrogels showed good antimicrobial drug delivery capacity. The properties of the developed cohydrogels demonstrated that they could be used as delivery vehicles for antimicrobial drugs. Cell proliferation study suggested that the cohydrogels supported the proliferation of the human keratinocytes.     

Evaluation of the impact of the surrounding urban morphology on building energy consumption

Empirical models of minimum (T_min), average (T_avg) and maximum (T_max) air temperature for Singapore estate have been developed and validated based on a long-tem field measurement. There are three major urban elements, which influence the urban temperature at the local scale. Essentially, they are buildings, greenery and pavement. Other related parameters identified for the study, such as green plot ratio (GnPR), sky view factor (SVF), surrounding building density, the wall surface area, pavement area, albedo are also evaluated to give a better understanding on the likely impact of the modified urban morphology on energy consumption.The objective of this research is to assess and to compare how the air temperature variation of urban condition can affect the building energy consumption in tropical climate of Singapore. In order to achieve this goal, a series of numerical calculation and building simulation are utilized. A total of 32 cases, considering different urban morphologies, are identified and evaluated to give better a understanding on the implication of urban forms, with the reference to the effect of varying density, height and greenery density. The results show that GnPR, which related to the present of greenery, have the most significant impact on the energy consumption by reducing the temperature by up to 2 °C. The results also strongly indicate an energy saving of 4.5% if the urban elements are addressed effectively.     

Submerged membrane bioreactor using fly ash filters: trials with distillery wastewater

This work presents preliminary results for distillery wastewater treatment in a MBR equipped with filters prepared from waste fly ash. The system was fabricated locally and employed submerged membranes in the 2-8 microm pore-size range. Distillery wastewater, after anaerobic digestion, was used as the feed and the bioreactor was inoculated with sludge obtained from a local distillery unit. The MBR was operated for around 250 days. The wastewater quality was monitored in terms of COD (chemical oxygen demand), colour, phenol, and MLSS (mixed liquor suspended solids) concentration. An average COD and phenol removal of 36% and 60% respectively was obtained. The maximum suspended solids retention by the ash filter was as high as 98%. The results were encouraging and further trials are currently underway to improve the performance.     

Optical and transport properties and electronic structure of nickel doped arsenic chalcogenides

The electronic structure of monoclinic As₂X₃ (X = S, Se) is investigated using full potential linearized augmented plane wave method in the framework of density functional theory. From energy bands and the density of states it is seen that the lone pair p-states of sulfur/selenium contribute closest to Fermi energy level. Introduction of transition metal impurities such as Nickel modifies the semiconducting gap in As₂S₃ and As₂Se₃. The crystal field splits the Ni 3d bands with t_2g electrons in the valence band and e_g electrons in conduction band. We compute optical properties like the complex dielectric functions, refractive indices, absorption coefficient, reflectance, etc. The low symmetry chalcogenides exhibit optical dichroism. On doping, As₂S₃ and As₂Se₃ show additional losses in the IR regions, which indicates allowed interband transitions due to available 3d-states in the valence and conduction bands. A narrow transparent window in the visible region is available in Ni_0.5As_1.5Se₃ crystals. Important transport properties such as Seebeck and Hall coefficients, and carrier concentration are computed. It is seen that these high resistivity chalcogenides are n-type semiconductors.     

Electronic structure of layer type tungsten metal dichalcogenides WX2 (X = S, Se) using Compton spectroscopy: Theory and experiment

In this paper, we report the first ever experimental Compton profile study of WS₂ and WSe₂ employing 20 Ci ¹³⁷Cs Compton spectrometer. To interpret our experimental data, the electronic properties of these compounds have been determined by linear combination of atomic orbitals, full potential linearised augmented plane-wave and spin polarised relativistic Korringa–Kohn–Rostoker (SPR-KKR) schemes. The band structure calculations show that both the WS₂ and WSe₂ are indirect-gap semiconductors. The SPR-KKR calculations are found to be relatively in poor agreement with the experimental electron momentum densities. The relative nature of bonding in both the dichalcogenides is explained in terms of equal-valence-electron-density profiles, Mulliken's population and valence band charge densities.     

Supercriticial fluid extraction of flavors and fragrances from Hyssopus officinalis L. cultivated in Iran

Hyssopus officinalis L. (hyssop) as a food ingredient has its own importance in flavor industry and also in sauce formulations. Supercritical fluid extraction (SFE) of hyssop, cultivated in Iran, was performed at various pressures, temperatures, extraction (dynamic and static) times and modifier (methanol) concentrations using an orthogonal array design with an OA₂₅(5⁵) matrix conditions. Pressure, temperature and modifier in the SFE system influenced the extraction yield. Also, the composition of the extracted oils was greatly impacted by the operating conditions. Main components of the extracts under different SFE conditions were sabinene (4.2–17.1%, w/w), iso-pinocamphene (0.9–16.5%) and pinocamphene (0.7–13.6%). The extraction of sabinene, for example, was favored at 100 atm, 55 °C, 1.5% (v/v) methanol, 30 min dynamic time and 35 min static time. Use of SFE under different conditions can allow targeting the extraction of different constituents.     

Meliorated oxygen reduction reaction of polymer electrolyte membrane fuel cell in the presence of cerium-zirconium oxide

Oxygen Reduction Reaction (ORR) kinetics is known to be one of the major bottle necks in PEM Fuel Cell performance. Several attempts are being made to enhance the ORR. Inspite of several attempts Pt in the vicinity of high surface area oxide catalysts seems to be the best choice although some alloy catalyst have shown good performance in half cell studies and single cell studies. We are investigating methods to improve the performance of PEM fuel cell especially in low air flow conditions which is the condition that will arise in surge power requirements. We have found that oxygen reduction reaction (ORR) performance of Pt/C can be increased in the presence of cerium-zirconium oxides especially Ce_0.8Zr_0.2O₂ (CZO) in the cathode catalyst layer. Ce_0.8Zr_0.2O₂ was prepared by co-precipitation method and the formation is confirmed by the XRD results. An XPS study of Ce 3d emission spectra dominated by atomic multiplet effects in core level spectroscopy of Ce_0.8Zr_0.2O₂-Pt/C are studied from which the possible oxidation states of Ce on Ce_0.8Zr_0.2O₂-Pt/C surface are examined. The ORR improvement in the CZO added electrodes have been studied using chronoammperometry and fuel cell testing.